Journal of the Korean Physical Society

pISSN 0374-4884 eISSN 1976-8524
Qrcode

Article

Condensed Matter

J. Korean Phy. Soc. 2011; 59(3): 2268-2274

Published online September 15, 2011     https://doi.org/10.3938/jkps.59.2268

Copyright © The Korean Physical Society.

Large Low-energy Oscillator Strength for Eu 4f Electrons of a Rare-earth Zintl Compound: EuIn2P2

Nirpendra Singh, Joo Yull Rhee

Abstract

A newly found Zintl compound EuIn2P2 has been investigated within the density-functional theory, and results of a detailed investigation of its electronic structure and related properties are reported. We employed the so-called LSDA+U method (LSDA: local-spin-density approximation) with varying U from 0 eV to 7 eV to take into account the strong on-site Coulomb repulsion between the Eu 4f -electrons and to reproduce the semiconducting energy gap of 3.2 meV experimentally observed by J. Jiang and S. M. Kauzlarich [Chem. Mater. 18, 435 (2006)]. The calculations, however, could not reproduce the energy gap even for the largest U value of 7.0 eV because the experimental gap was not an optical gap, but it was deduced from the temperature dependence of resistivity at 26 − 60 K; thus, the experimental gap was not a real ¡®semiconducting¡¯ gap. The calculated optical-conductivity spectrum with U = 7.0 eV could not reproduce the experimental spectrum, while with simple LSDA, the calculated spectrum resembled the experimental one rather successfully. Therefore, it seems that the LSDA+U method is not suitable to correctly simulate the optical properties of this compound. Contrary to the expectation, we found that EuIn2P2 had a large oscillator strengths for f ! d transitions in the low-energy range (below 1.5 eV); i.e., the peaks located at ¡­0.6 eV and ¡­1.1 eV in the experimental spectrum are mainly due to transitions from f -bands to d-bands, in which joint density-of-states effects play a key role. We also found that the magneto-optical Kerr effect was quite large in the EuIn2P2 compound.

Keywords: LSDA+U, Electronic structures, Optical properties, Density-functional calculations, Rare-earth Zintl compound